it is very important to have the throttle pressure valve linkage to save the tranz from burning up
a 2-v linkage can be mod o fried to work with very little work
if it has a flat rod from bracket to the carb stud
you can bolt 2 of those together to make it longer from the bell crank to carb stud
if its round threded rod you can cut and weld a piece in to make it longer and still be adjustable
usally needs 1" to 1.5" added to the linkage to be long enuff
I also bend in a slight s curve to aline it up to the carn stud
it needs to move freely with out the carb lever and the spring pull it back with out open the throttle
stock 4-v linkage would be ideal,IIRC it would be the 3 rod style for A-body
it will be a boost in performance even with the 2-v wimpy cam in the 318
4-v and headers will wake it up some,cam swap later to gain some more performance
done this swap many times over the yrs
should be a thermo bog on that 340,I would have it rebuilt or go with another carb,they can be pricey and feniky to get right for a first timer
600cfm eddie carb works great on them,IMO
here is the 88 360 headed 318 4-v cop engine in my stepside
600 eddie carb
LD4B intake
lunati voodoo roller cam
headers
deul 2.5 pipes
a999 HS/LU tranz
8 3/4 with 3.23 gears
runs strong and knocks back 19 mpgs daily driveing